Arrangement for a low-noise and low-shock interception of moving masses

ABSTRACT

In the illustrated embodiments, an elastomer body has a relatively thin metal layer overlying the elastomer surface to be loaded so as to prevent adhesion at the elastomer surface in spite of a long period of dwell in contact with a relatively more rigid cooperating part such as a hard rubber stop. In a basic form, a thin metal sleeve may encircle a cylindrical elastomer body. The outer surface of the sleeve may be grooved for extra adhesion resistance. In a further development, the sleeve is formed as a helical wire spring which may be confined between two flanges integral with the elastomer body.

This is a continuation of application Ser. No. 870,439, filed Jan. 18,1978, now abandoned.

BACKGROUND OF THE INVENTION

The subject of the invention is an arrangement for the low-noise andlow-shock interception of moving masses employing a damping stop meanswhich is formed from a body consisting of elastomer.

In numerous technical applications it is necessary to intercept a movingmass with a low noise and low shock or to limit a mechanical movement toa given path length or stroke. In precision engineering, damping stopmeans consisting of elastic material is used to overcome this problem.In practical operation, damping elements may consist of an elastomer, inparticular the material known under the trade name "Viton", the chemicalname for which is "vinylide fluoride-hexafluorpropylene-copolymerisate"(DIN 47020=ISO/R 1629-1971). This material exhibits good damping undershock load with low shock noise. However, these materials have thedisadvantage that after a long period of dwell against the stop means,the detachment of the moving mass is hindered by adhesion at theelastomer surface. The adhesive effect is dependent upon thetemperature, the strength of the preceding shock and the bearing force.In precision engineering, for example in a teleprinter or a printer fora data processing installation operating at high switching speeds, evendelay times of approximately ten milliseconds (10 msec) areimpermissibly long. Furthermore, in the known damping elements, after along period of operation and under a fluctuating surroundingtemperature, an impermissible wear and plastic deformation also occur.In the case of stop means having a decelerating effect, the considerablestray width of (range of variation in) the friction coefficient is alsooften disturbing, as this gives rise to a very different deceleratingand lifting behaviour. The effects of specific lubricants on the knowndamping elements can further intensify these disadvantageous influencesdue to chemical changes.

In the known damping stop means, in various applications, the adhesiveeffect was counteracted by means of increased restoring forces on themoving mass. Furthermore, in order to avoid the above mentioneddisadvantages, the operating time and the operating temperature rangewere limited. An automatic rotation of the damping stop means followinga suitable transit time is also already known. A deliberate and limitedlubrication has also partially led to an improvement.

SUMMARY OF THE INVENTION

The aim of the invention is to avoid the disadvantages of the knowndamping stop means without impairing the excellent damping properties.

This aim is realized in accordance with the invention in that on itssurface which is to effect the intercepting the body has a metal layer,the thickness of which is substantially less than the thickness of thebody.

The new arrangement has the advantage that even in the case of a longperiod of dwell, the supported mass does not adhere to the surface ofthe damping stop means. Even with a high surface pressure, no flatteningoccurs at the contacting surface of the damping stop means as the shapeof the contacting surface is maintained by means of the elastic metallayer (elastic because of the elastic body backing). No disturbing wearoccurs. The direct contact between the elastomer and the counter stopmeans is avoided. There is no additional adhesive influence by achemically or physically changed surface of the elastomer due tolubricants or temperature fluctuations. The friction coefficientstraying is considerably reduced. The positive properties regardingnoise- and shock-damping are retained in full.

An advantageous further development consists in that the elastomer bodyis designed to be cylindrical and a metal sleeve is applied to theperiphery of the body.

A particularly advantageous further development of the new damping stopmeans consists in that on its periphery the elastomer body is providedwith a wide groove which at its sides is laterally bounded by flanges,and that in the groove at the periphery of the body there is positioneda helical spring, the wire diameter of which is considerably smallerthan the wall thickness of the body.

Details of the invention will be explained making reference toadvantageous exemplary embodiment which are illustrated in the Figuresof the accompanying sheet of drawings; other objects, features andadvantages of the invention will be apparent from this detaileddisclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a fundamental arrangement for a moving mass and adamping stop means in accordance with the invention;

FIG. 2 illustrates a new damping stop means in accordance with theinvention detached from its mounting arrangement (which may, forexample, correspond to that shown in FIG. 1);

FIG. 3 illustrates an advantageous further development of the newdamping stop means; and

FIG. 4 illustrates a particularly advantageous further development ofthe new damping stop means.

DETAILED DESCRIPTION

FIG. 1 shows a fundamental arrangement of a moving mass with a dampingstop means. The moving mass is the metal lever 1 which is pivotableabout an axis 2. The drive system for moving the lever is not shown inFIG. 1. This can be a mechanical, hydraulic or magnetic drive system.The lever 1 is pivoted in the two arrow directions r and 1 (l). Thepivot range is defined by the two stop means 3 and 4. Fundamentally itis possible to design the two stop means 3 and 4 asparallelepiped-shaped, buffer-shaped or cylindrical bodies composed ofelastomer and to coat (or cover) these with a metal layer at the loadedsurface. The metal lever 1 would then directly strike against thedamping stop means which are to serve to limit the movement play.

FIG. 1 illustrates an exemplary embodiment in which the body of thedamping element 5 is either fixed or arranged to be rotatable on an axis6 on the moving lever 1. For example, the element 5 may consist of anelastomer cylinder with a central axial bore at axis 6 for mounting ofthe cylinder on lever 1, and an annular layer of metal for contactingthe stop means 3 and 4. This embodiment has the advantage that only onedamping element is required which, when the lever is deflected into thetwo directions, abuts against the stop means 3 and 4 and limits themovement.

FIG. 2 is an enlarged cross-sectional view of a damping stop means 5a,representing a first embodiment of the damping stop means 5 of FIG. 1.The damping stop means 5a consists of a cylindrical body 7 composed ofelastomer which is provided with a bore 8 for receiving a suitablemounting element such as the pin or shaft at axis 6 in FIG. 1. The body7 can either be firmly screwed in position (or otherwise non-rotatablysecured to lever 1, for example) or rotatable on an axis (such as theaxis indicated at 6 in FIG. 1, for example). The major part of theperiphery is surrounded by a metal sleeve 9. The side elevational viewof sleeve 9 and of body 7 conforms with that shown for damping stopmeans 5 in FIG. 1. The wall thickness a of the metal sleeve 9 isconsiderably less than the wall thickness A of the cylindrical body 7.The metal sleeve is either pushed, pressed or glued onto the body 7 andsolely supported thereby. When stop means 5a is mounted on the lever 1and the movement of the lever 1 is limited, the cylindrical metalsurface 9a of the damping stop means 5a abuts against the lateralcounter stop means 3 and 4 (FIG. 1).

FIG. 3 illustrates a further development designated by reference numeral5b of the damping stop means shown in FIG. 2. The difference consists inthat the generally cylindrical surface 10a of the metal layer 10 is notflat, but is corrugated or grooved. This further development has theadvantage that no adhesive effect occurs on the otherwise flat surface,in particular when oils, fats or other liquids are applied thereto.

FIG. 4 illustrates a particularly advantageous further development ofthe new damping stop means. The damping stop means of FIG. 4 has beenassigned reference numeral 5c to indicate that it may be mounted onlever 1 as shown for stop means 5 in FIG. 1. The cylindrical body 7'with the bore 8' is provided at its periphery with a wide groove 11which is bounded at the two end sides by annular flanges 12 and 13respectively. A helically wound spring 14 is arranged in the groove 11.The turns of the helical spring are arranged closely next to oneanother. The diameter d of the spring wire is considerably smaller thanthe wall thickness D of the body 7'. The wire diameter is to amount toapproximately 1/5 or less of the wall thickness D of the body 7'. Theknown good noise- and damping-properties of elastomers are retained. Thedesign of the damping stop means 5c illustrated in FIG. 4 isparticularly advantageous because a particularly cost-favorableproduction is possible. The helical spring can be produced very cheaplyin large numbers. The fixing on the elastomer body in the groove 11 isparticularly simple since the helical spring is merely screwed onto oneof the two flanges 12 and 13. The two flanges serve to prevent a lateraldisplacement of the spring 14. This produces a particularly simplecomponent which can be used universally. The damping stop meansillustrated in FIG. 4 can also be used as counter stop means, forexample in place of the stop means 3 and 4 in FIG. 1. For this purposethe damping stop means is secured by the bore 8' to the wall (which wallwould extend parallel to the plane of FIG. 1), with the bore 8' disposedtransversely to the direction of movement of the lever 1, or with stopmeans 5c arranged to be rotatable on a central longitudinal axis of bore8'. The lever 1 is then intercepted by the generally cylindrical surface14a of the helical spring 14. On account of the elastic spring 14, thearrangement in FIG. 4 exhibits an even better shock elasticity. In placeof the spiral spring, a metal sleeve can also be inserted into thegroove 11. This can be effected, for example, by injecting or castingthe elastomer body into the metal sleeve.

In each of the embodiments of FIGS. 2, 3 and 4, the thickness (such as aor d) of the metal layer (9, 10 or 14) which contacts the stop means(such as 3 and 4 in FIG. 1) is not greater than about one-fifth thethickness (A or D) of the supporting elastomer of the body (7 or 7').

It will be apparent that many modifications and variations may beeffected without departing from the scope of the novel concepts andteachings of the present invention.

We claim as our invention:
 1. In a printing instrument or the like, suchas a teleprinter or a printer for a data processing installation, in thefield of light manufacturing of precision engineered equipment, andwherein a pivotal lever is to be set in motion from a rest condition inengagement with a fixed stop, an arrangement for retaining such lever inthe rest condition while minimizing adhesion forces resisting separationfrom the fixed stop, and yet serving for the low-noise and low-shockinterception of the moving lever upon return to such rest condition,said arrangement comprising a damping stop means on one of said leverand fixed stop for engaging a cooperating surface on the other of saidlever and fixed stop to define a rest position of the lever and formedfrom a body consisting of elastomer (7 or 7'), characterized in that atthe active surface of the body which is to engage the cooperatingsurface, the body has a metal layer (9, 10 or 14), the thickness (a ord) of which is considerably less than the thickness (A or D) of theelastomer (7 or 7'), the metal layer being supported solely via theunderlying elastomer, said damping stop means comprising the support ofthe metal layer solely via the underlying elastomer and the relativethinness of the metal layer providing low-noise and low-shockinterception of the moving lever upon return to said rest conditionwhile minimizing adhesion forces resisting separation of the dampingstop means from the cooperating surface in spite of a long period ofdwell with the damping stop means in contact with such cooperatingsurface.
 2. An arrangement according to claim 1, wherein the elastomer(7 or 7') has a curved convex configuration for confronting thecooperating surface, and the metal layer (9, 10 or 14) being curved inconformity with the curved convex configuration of the elastomer (7 or7') so as to have a line type of contact with the cooperating surface inthe rest condition.